The Collaborative International Dictionary of English v.0.48:

necklace \neck"lace\ (?; 48), n.
   1. A string of beads, etc., or any continuous band or chain,
      worn around the neck as an ornament.
      [1913 Webster]

   2. (Naut.) A rope or chain fitted around the masthead to hold
      hanging blocks for jibs and stays.
      [1913 Webster]

WordNet (r) 3.0 (2006):

necklace
    n 1: jewelry consisting of a cord or chain (often bearing gems)
         worn about the neck as an ornament (especially by women)

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "necklace":
   anklet, armlet, band, bangle, beads, belt, bijou, bracelet,
   breastpin, brooch, chain, chaplet, charm, chatelaine, cincture,
   cingulum, circle, collar, collarband, coronet, crown, diadem,
   earring, ecliptic, equator, fascia, fillet, finger ring, fob, gem,
   girdle, girt, girth, great circle, hoop, jewel, locket, neckband,
   nose ring, pin, precious stone, quoit, rhinestone, ring, stickpin,
   stone, tiara, torque, wampum, wristband, wristlet, zodiac, zone